p. hlavenka et al- near infrared second overtone cw-cavity ringdown spectroscopy of d2h^+ ions
Post on 06-Apr-2018
214 Views
Preview:
TRANSCRIPT
-
8/3/2019 P. Hlavenka et al- Near infrared second overtone cw-cavity ringdown spectroscopy of D2H^+ ions
1/7
International Journal of Mass Spectrometry 255256 (2006) 170176
Near infrared second overtone cw-cavity ringdownspectroscopy of D2H
+ ions
P. Hlavenka a, R. Plasil a, G. Bano b, I. Korolov a, D. Gerlich c,J. Ramanlal d, J. Tennyson d, J. Gloska,
a Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, 180 00, Prague, Czech RepublicbResearch Institute for Solid State Physics and Optics, HAS, Budapest, Hungary
cInstitut f ur Physik, Technische Universitat, 09107 Chemnitz, Germanyd Department of Physics and Astronomy, University College London, London WC1E 6BT,UK
Received 25 November 2005; received in revised form 2 February 2006; accepted 3 February 2006
Available online 13 March 2006
Abstract
A study of D2H+ ions in their lowest rotational states is presented. The ions are generated in pulsed discharge in liquid N 2 cooled He/Ar/H2/D2
gas mixture. Near infrared (NIR) second overtone transitions in the 65346536 cm1 (1.5291.530m) region are used to identify the ions and
determine their degree of rotational excitation. The data were obtained using NIR cavity ringdown absorption spectroscopy (NIR-CRDS). The
sensitivity obtained was typically 5 109 cm1. The measured second overtone transition frequencies are in very good agreement (better than
0.02 cm1) with ab initio predictions. From the Doppler broadening the kinetic temperature of ions is estimated to be (220 50) K. The absolute
number density of D2H+ as a function of H2/D2 mixing ratio and time is measured.
2006 Elsevier B.V. All rights reserved.
Keywords: D2H+; Cavity ringdown spectroscopy; Second overtone; Hydrogen plasma; Deuterium plasma
1. Introduction
Since hydrogen is by farthe most abundantelement in theuni-
verse, with molecular hydrogen dominating in the cold regions,
the formation and destruction of H3+ ions is of great astrophys-
ical significance. The discovery of H3+ in diffuse interstellar
molecular clouds [1,2] has confirmed the long expected pres-
ence ofH3+ in space and has reopened interest in the problem of
the interaction of this simplest polyatomic molecular ion with
electrons and with molecules. The ions H3+ and its deuterated
isotopologues (H2D+, D2H
+ andD3+) play importantroles in the
kinetics of media of astrophysical interest [3,4], planetary atmo-
spheres [4] and also in laboratory produced plasmas. Thephysics
of H3+ gets more complicated when deuterationprocesses [46],
which are driven by exothermicity of H/D exchange reactions,
have to be considered in plasma environment. It has long been
anticipated that enhanced isotopic fractionation effects should
Corresponding author. Tel.: +420 221 912 329; fax: +420 284 685 095.
E-mail address: juraj.glosik@mff.cuni.cz(J. Glosk).
occur in cold interstellar regions driven by the fact that deuter-
ation is energetically down hill [7].
Recently, millimetre and sub-millimetre spectroscopy of the
dense interstellar medium has shown that, in cold dense regions,
deuterated molecular species are highly abundant, in some cases
reaching more than 10% of their nondeuterated analogues. This
is a very high number if we consider that the general cosmic
abundance of D is about 105 that of H. Surprisingly, dou-
bly and triply deuterated species can be observed [811]. These
observations stimulated an intensive search for H2D+ and D2H
+
ions [10]. The key work in the astronomical search for D2H+
is the laboratory measurement of the para ground-state transi-
tion by Hirao and Amano [12,13] and theoretical calculations by
Ramanlal and Tennyson [14,15]. The search led to the detection
of H2D+ andD2H
+ in colddenseinterstellar clouds [8,10]. These
observations have heightened interest in further laboratory and
theoretical studies of partially deuterated molecular ions.
The kinetics of the formation of H3+, H2D
+, D2H+ and D3
+
ionsin H2/D2 containing plasmas is well understood at least at
room temperature. Relevant rate coefficients and products of ion
molecule reactionswere successfully studied usingswarm (SIFT
1387-3806/$ see front matter 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.ijms.2006.02.002
mailto:juraj.glosik@mff.cuni.czhttp://dx.doi.org/10.1016/j.ijms.2006.02.002http://dx.doi.org/10.1016/j.ijms.2006.02.002mailto:juraj.glosik@mff.cuni.cz -
8/3/2019 P. Hlavenka et al- Near infrared second overtone cw-cavity ringdown spectroscopy of D2H^+ ions
2/7
P. Hlavenka et al. / International Journal of Mass Spectrometry 255256 (2006) 170176 171
[16,17]), beam and RF ion trap experiments [18]. The kinet-
ics gets particularly complicated at low temperatures, where
ortho and para states and nuclear spin restrictions have to be
considered [1823]. The main challenge for future experiments
is a state-to-state description of the underlying ionmolecule
reactions. Equally important is to understand the recombination
processes; again internal excitation of the ions has to be explic-
itly considered and hence determined [24]. Differences in rates
and products branching ratios of dissociative recombination of
H3+, H2D
+, D2H+ and D3
+ ions may also be partly responsible
for the enhanced population of deuterium [5,25].
However, despite enormous efforts, the results of experi-
mental studies aimed at determining the rate of recombina-
tion of H3+ and D3
+ ions with electrons have been found to
yield values that vary by at least one order of magnitude from
1 108 to 3 107 cm3 s1 for H3+ [2630] and 2 108
to 2 107 cm3 s1 for D3+ [24,3135]. Poor characterisation
of internal excitation of recombining ions in these experiments
may well be at least partly responsible for these discrepancies.
Very recent experiments with rotationally cold ions indicate thatrotational excitation of H3
+ can have a significant influence on
the recombination rate coefficient of these ions [3641]. These
recent measurements largely agree with the recent and success-
ful theoretical studies of dissociative recombination of H3+ and
D3+ made by Kokoouline and Greene [24,42,43]. Despite the
good agreement that has recently emerged between theory and
the storage ring experiments, the case of recombination of H3+,
H2D+, D2H
+ and D3+ ions with electrons is far from closed.
The motivation of the present study of D2H+ using over-
tone spectroscopy in low temperature plasma is the search for
a tool for simple in situ characterisation of the internal state
of the reacting/recombining D2H
+
ions. Results of the presentexperiments will be used in parallel studies of laser induced
ionmolecule reactions (LIR) carried out in a low tempera-
ture RF trap. For such studies very accurate transition fre-
quencies are required [4448]. Our approach can be simply
stated. We use high sensitivity and high resolution Near Infrared
Cavity Ringdown Absorption Spectroscopy (NIR-CRDS) to
obtain the second overtone absorption spectra of D2H+ ions
in their lowest rotational states. These spectra are then used
to monitor the concentration and rotational population of the
ions.
2. Experimental
2.1. Test tube
To study recombination of differentinternal statesof H3+-like
ions we have recently built a test tube apparatus. In the present
experiment D2H+ ions were produced in pulsed microwave dis-
charge in He/Ar/H2/D2 mixture. The discharge was ignited by
4 ms long pulses of microwave (60120 W) in a waveguide with
repetition period 10 ms inside a silicate glass tube with internal
diameter of 2.3 cm. After adjustment, the plasma column has
effective length5cm. Fig. 1 shows a schematic diagram of the
apparatus and indicates position of mirrors of the optical cavity,
which is described in detail in next section. The discharge tube
Fig. 1. Schematic diagram of the test tube. The pulsed microwave discharge
takes place in a liquid nitrogen cooled tube. For CRDS two highly reflective
mirrors are mounted on tilt stages inside the vacuum.
actually has double walls and the space between the tubes is
filled by liquid nitrogen to cool the buffer gas and plasma.
Since already impurities of a few ppm lead to a loss of
the D2H+ ions within a millisecond, the apparatus is based
on UHV technology and all reactant gases pass through liquid
nitrogen traps. He ions and metastable atoms created during
the microwave discharge are rapidly converted to H3+ (and
deuterated analogues) by a sequence of ionmolecule reactions
involving Ar+ and ArH+ as intermediate ions. The production
scheme is well known andhas been previously verified by kinetic
modelling and mass spectrometric observations in FALP (Flow-ing Afterglow Langmuir Probe) and SA (Stationary Afterglow)
[35]. In addition in the presence of hydrogen and deuterium
the formation of H3+, H2D
+, D2H+ and D3
+ takes place. At
68 mbar the total gas flow tot was around 800 sccm (standard
cubic centimetre per minute) with the He/Ar/H2/D2 ratio
equal to 800/1.3/1/(0.051).
The time constants for ion-molecule reactions are some tens
(20) of microseconds at the gas partial pressures used. The
partial population of individual ions and the degree of deutera-
tion depends on the temperature and on the partial pressures of
hydrogen and deuterium. As the primary aim of this paper is the
experimental determination of transition frequencies in the NIRregion, we focused on achieving high concentration of D2H
+
in the lowest rotational states rather than on kinetics studies of
processes in plasma discharge. Once the transition frequencies
are known, the D2H+ ions can be studied at even lower number
densities.
2.2. CRDS absorption spectroscopy
Transition frequencies and intensities for the H3+, H2D
+,
D2H+ and D3
+ ions have been calculated with high precision
[15,49] and some transitions were observed in the microwave
(see e.g., [50]) and Mid-IR [22]. However, there is no exper-
-
8/3/2019 P. Hlavenka et al- Near infrared second overtone cw-cavity ringdown spectroscopy of D2H^+ ions
3/7
172 P. Hlavenka et al. / International Journal of Mass Spectrometry 255256 (2006) 170176
Fig. 2. Set-up of the cw-CRDS experiment: The laser beam from fibre-coupled
telecom DFB laser diode is collimated to a free beam, passing though an optical
isolator, acousto-optic modulator (AOM), that acts as a fast optical switch and
matched by a spatial filter to mode TEM00 of optical cavity (l = 0.75 m) com-
posed of two concave mirrors M1 and M2(r= 1 m) with reflectivity 99.990%.
The entrance mirror is mounted on a piezo transducer. The signal behind second
mirror is detected by InGaAs avalanche photodiode (APD) and recorded by a
computer. A cut-off filter suppresses the light emission of plasma. A wavemeter
and a FabryPerot etalon are used for wavelength calibration.
imental data on the second overtone region for the deuterated
species.
The high sensitivity of continuous wave cavity ringdown
spectroscopy (cw-CRDS) makes the technique suitable for
investigating the spectra of ions and radicals in plasma [51].
The physical principles of cw-CRDS have been described in
numerous publications (see, for instance [52,53] and references
cited therein). The present NIR-CRDS set-up is a modification
of the version used in our previous work on H 3+ recombination
studies [44,54,55] where a detailed description of our NIR-CRD
spectrometer can be found. The actual set-up used in the present
experiments (see Fig. 2) is based on a fibered DFB laser diode.In CRDS experiments, the exponential decay of the intensity
of the laser light coupled into a high finesse optical cavity is
measured. The characteristic decay time depends on losses in
the resonator and on absorption by the medium that is enclosed
in the cavity. Each intensity decay (ringdown) is fitted by an
exponential function. Without absorbing media a typical decay
time 0 was31s. The value 0 is a property of the resonator
and varies littlewith the frequencychange.The actual absorption
coefficient of the absorbing medium can be directly calculated
from the measured decay time (ringdown time)
= 1
0
1
d
l c
,
where c is the speed of light, d the length of cavity, and l is
the length of the plasma. Theoretically, 1/0 should appear as
a smooth baseline of 1/, and it should be straightforward to
obtain the required (1/0 1/). This subtraction can be com-
plicated by disturbance of the baseline, such as an etaloning
effect caused by a back-reflection (on any optical component)
of the light leaking from the resonator. This can be suppressed by
positioning all elements at a slight tilt from the axis. In our setup
the liquid nitrogen cooling of the discharge tube affected the
thermal, thus mechanical, stability of the rigid cavity construc-
tion and resulted in non-deterministic modulation of the baseline
in time. This made the subtraction of baseline unreliable and a
synchronous detection with a direct 0 measurement had to be
developed.
2.3. Synchronous detection
An advanced time resolved CRDS data acquisition system
has been developed for our previous studies of H3
+ recom-
bination [54]. For the data evaluation the time (delay from
the synchronisation pulse) at which each ringdown started was
recorded. Using this additional information and by applying an
iterative algorithm we are able to monitor the fast decay of
the ion number density caused by recombination. This tech-
nique proved able to monitor absorption variations with time
constant below 50s. For a more detailed description see
[54,56].
As the aim of the present experiment was to determine
transition frequencies, we have used slower modulation of the
microwave power to reduce the noise in the electronics circuits.
Monitoring of the ion number density with CRDS remains as
fast as in the previous experiments. Fig. 3 shows the time evolu-tion of the H3
+ and D2H+ ion number density during the active
discharge and during the post discharge period. Approximately,
3 ms after switching off the microwave the absorption sig-
nal drops to zero. For transition frequency measurements we
selected two sets of ringdowns; those in the time range 1.54 ms
are treated as signal and those in the range 7.510 ms, where
the absorption can be neglected, give the baseline at a particular
wavelength.
Fig. 3. Time evolution of number densities during the measurement period,
measured on the centre of absorption peak. Upper panel: D2H+(v = 0) number
density according to the 202 313 transition. The ratio D2/(D2 + H2) was 0.4.
Lower panel: H3+(v = 0) number density, measured on the centre of v2 = 30
(P22) H3+ transition at 6877.546cm-1. Marked are the timeintervals correspond-
ing to Signal and to Background (baseline), used by synchronous detection
for determination ofand 0 respectively. The assumptions used in the density
calculations are discussed in text.
-
8/3/2019 P. Hlavenka et al- Near infrared second overtone cw-cavity ringdown spectroscopy of D2H^+ ions
4/7
P. Hlavenka et al. / International Journal of Mass Spectrometry 255256 (2006) 170176 173
To test the synchronous detection and to characterise the
properties of the discharge a known [57] v2 = 3 0 (P22) H3+
line was measured. From the measured absorption of ions in one
single state one can derive the overall ion number density, if one
assumes rotational equilibrium and hence a rotational tempera-
ture. At T = TKinIon = TRot = 180 K, derived from Doppler broad-
ening, the absorption coefficient in the line centre is, according
to [58], 1.13 1018 cm1 per molecule cm3. Using this value
gives an H3+ number density during the discharge of [H3
+]
2.51011 cm3. This value is in good agreement with our
previous H3+ measurements in similar conditions [17,54].
2.4. Wavenumber retrieval
The DFB laser diode was scanned with constant laser cur-
rent by a computer controlled temperature scan. A FabryPerot
etalon was used to linearise the wavenumber scale. During all
D2H+ scans the absolute wavenumber position at each wave-
length was obtained from a wavemeter based on a Michelson
interferometer with a temperature stabilised He-Ne laser refer-ence. The wavemeter was constructed recently in our laboratory
as a modification of the design described in [59]. In order to
obtain the line positionswith high accuracy, an in situ calibration
of the wavemeter has been accomplished. For this calibration we
used CRD spectra of traces of HDO and H2O at room tempera-
ture desorbed from the liquid nitrogen trap of the D 2 inlet. We
compared them with the recently published data on NIR spectra
of H2O and HDO [60]. The calibration procedure was repeated
several times during the experiment confirming the high stabil-
ity and accuracy of the system. We estimate the accuracy of the
wavenumber calibration to be better than 0.002 cm1.
3. Results and discussion
3.1. Measurements of absorption spectra; transition
frequencies of D2H+(v = 0) ions
The NIR second overtone absorption spectrum of
D2H+(v = 0) was obtained by scanning over the region
6534 6537 cm1 (corresponding to 1.5291.530m).
Examples of measured absorption lines are plotted in Fig. 4.
The transition frequencies obtained are listed in Table 1.
Note that the measured transitions form a clear series. The
in situ calibration enables us to measure frequencies with
accuracy 0.002 cm1.The experiment was guided by the use of transition frequen-
cies predicted using the ultra-high accuracy ab initio model of
Fig. 4. Second overtone absorption spectra (v1 + 2v3 0) of D2H+ measured
by NIR-CRDS in modulated microwave discharge. Full lines indicate the best
fits by Gaussian function. From the Doppler broadening of absorption lines the
kinetic temperature TKinIon = (22050) K of ions in the microwave discharge
wascalculated. The rotational temperature TRot = (21050) K wasestimatedby
comparing the peak areas corresponding to 202 and 000 rotational ortho states.
Polyansky and Tennyson (PT) [49], as applied by Ramanlal and
Tennyson [15]. Assignments were made by analysing the cal-
culated energy levels of D2H+. As can be seen from Table 1,there is excellent agreement between the measured and calcu-
lated transition frequencies.Indeed, this agreement is better than
thestill good agreement obtained in the H3+(v2 = 30) studies,
see studies in [54], the laser induced reaction study in [45] orthe
first overtone studies of H2D+ and D2H
+ by Farnik et al. [22].
While this excellent agreement must in part be dueto a fortuitous
cancellation of errors, there are two reasons why the PTs model
might be expected to work better for the transitions observed
here than for the other overtone transitions cited. Firstly, the
PTs model is particularly good at predicting the frequency of
pure stretching transitions (see [49,61]) and the present overtone
transitions involve one quantum of the v1
and two quanta of the
v3 stretching mode, and secondly deuteration reduces the effects
of the failure of the Born-Oppenheimer approximation which,
although allowed for extensively in PTs model, is still probably
the largest remaining cause of residual error in the calculations.
3.2. Measurements of kinetic and rotational ion
temperature
From the Doppler broadening of the measured absorp-
tion lines, the kinetic temperature of the D2H+(v = 0)
ions in the microwave discharge was calculated to be
TKinIon = (220 50) K. These results are consistent with data
obtained from the H3+ dominated discharge. The agreement isvery good if we consider small differences between discharges
in both mixtures He/Ar/H2 and He/Ar/H2/D2. The observed ion
Table 1
Second overtone transitions (v1 + 2v3 0) of D2H+ measured by NIR-CRDS
Ortho/para JKaKc
JKaKc
E[K] Wavenumber [cm1] Exp Theor Intensity [cm1/cm2]
Exp Theor
Ortho 202 313 146.3 6534.377(1) 6534.374 0.003 1.89109
Para 101 212 50.2 6535.950(1) 6535.943 0.007 9.681010
Ortho 000 111 0 6536.319(2) 6536.301 0.018 1.09109
Experimentally obtained transition frequencies, Exp, with error estimates, are compared to theoretically predicted frequencies, Theor [15].
-
8/3/2019 P. Hlavenka et al- Near infrared second overtone cw-cavity ringdown spectroscopy of D2H^+ ions
5/7
174 P. Hlavenka et al. / International Journal of Mass Spectrometry 255256 (2006) 170176
kinetic temperature is also in good agreement with our previ-
ous studies carried out at very similar conditions (using the test
tube). In these experiments we have obtained an enhancement of
the ion kinetic temperature during the microwave discharge by
70100K [54,56]. In these experiments, the microwaves were
switched off by a fast switch and during the early afterglow the
relaxation ofTKinIon from 370 to 300 K (buffer gas temperature)
was observed within 50s.
The comparison of the intensities corresponding to the two
ortho states, 000 and 202 of D2H+ (v = 0), gives a rotational tem-
perature TRot = (210 50) K (under the assumption of thermal
equilibrium). The intensity corresponding to para state 101 is
smaller by a factor two than would be expected from thermo-
dynamic equilibrium with the two observed ortho states. There
are two possible explanations for this: the two groups of ions
ortho and para states are not in thermodynamic equilibrium; or
the calculated values of absorption coefficient are not accurate
enough. It shouldbe noted that there were also some unexplained
discrepancies between the measured and calculated intensities
in the overtone study of Farnik et al. [22]. More detailed calcu-lations [62] completely failed to find any problems with the ab
initio procedure used in the calculations and hence the source
of this discrepancy (which actually only affected a single tran-
sition). In general, we are confident that intensities calculated
using the PTs model are reliable. Indeed, the discrepancy with
Farnik et al. remains the only one we are aware of, however,
it is difficult to be certain which of the two explanations given
account for the weaker than predicted para transition intensity.
When discussing these observations it is important to realise
that theplasma in themicrowavedischarge used in present exper-
iment is close to steady state, but it is not in thermodynamic
equilibrium. Usually such plasma can be described as an assem-bly of electron gas, ion gas and buffer gas consisting of
electrons, ions, and neutral atoms and molecules, respectively.
Electrons are hot, so they can excite ions [63,64] or recombine
with them. For the ions and buffer gas the situation is similar
to drift tube experiments, where ions are under the influence
of the electric field cumulating kinetic energy, but buffer gas
atoms (He in our case) are cold. In our previous experiment with
similar conditions in a microwave discharge, we verified that
the buffer gas is at the wall temperature by measuring absorp-
tion of H2O during a discharge and an afterglow [5456]. The
ions have kinetic energy EKinIon and corresponding TKinIon, this
temperature is coupled to Doppler broadening. The energy of
ionHe collision EColIon (and corresponding TColIon) is lowerthan EKinIon because the He atoms are cold. This EColIon deter-
mines the internal (rotational in our case) excitation of the ions.
This is only a qualitative picture but one which points at a differ-
ence between EKinIon and EColIon (for further reading see papers
on drift tube experiments where many aspects of this problem
are discussed including the reasons for introducing TKinIon and
TColIon [6568]). To understand the actual role of certain type
of collisions on the measured data we have to estimate the col-
lision frequencies under the conditions of our experiment. At
the partial pressures used in this experiment the frequency of
collisions of D2H+ ions can roughly be estimated as 2 108 s1
and 5
105
s1
for collisions with He and H2 (or D2), respec-
tively. The lifetime of D2H+ ions in a discharge is given by
recombination (diffusion can be neglected here) and this is (at
electron density ne 2 1011 cm3 and the recombination rate
coefficient 107 cm3 s1) equal to 50s. From these esti-
mates it follows that D2H+ ions, before recombining, will have
few collisions with H2/D2 and thousands with He. Few colli-
sions with H2/D2 areenough to quenchthe vibrational excitation
but are probably not sufficient to equilibrate ortho and para
states. There are probably enough collisions with He to establish
equilibrium within the distinct ortho and para groups at a tem-
perature corresponding to collisional energy of collisions with
He, EColIon (characterised by TColIon). Further studies dealing
with relaxation, spin conservation and state-to-state reactions in
hydrogen/deuterium plasma are required (see e.g., discussion
in [1823,40,44,46,47]); the present study is just a step toward
understanding these processes.
3.3. Measurements of ion number densities
Once transition frequencies for D2H+(v = 0) ions were estab-lished, we used the strongest transition at 6534.377 cm1 to
study theplasma. Themeasured variation of theabsolutenumber
densityofD2H+(v = 0)ionsis plotted in Fig.3. The calculation of
absolute number density wasmade under the assumption of ther-
mal equilibrium T = TKinIon = TRotIon = 220 K. The microwaves
were modulated, but nevertheless there was a time interval
(1.54 ms), where microwave power was constant and the ion
number density was nearly constant. This number density is the
one we consider as the ion number density in the discharge.
Considering quasineutrality and the dominance of the H3+
ion, one can assume that the electron number density is equal to
the measured H3+
ion density in H3+
test measurements. As wetried to keep the conditions used for H3+ and D2H
+ measure-
mentsclosetoeachother,wecanassumethattheelectrondensity
derived from the H3+ measurements is relevant to the D2H
+
measurements, where the ratio between different isotopologues
is unknown. From the plots in Fig. 3 we can see that number
density of H3+ and D2H
+ are almost the same. This is surprising
if we realise that D2H+ ions represent only a fraction of ions in
deuterium containing discharge. The observations indicate that
an overall ion number density in deuterium containing gas at
otherwise identical conditions is higher. This can be partially
explained by a significantly different behaviour of the discharge
with and without the D2 admixture. The lower recombination
rate coefficients of deuterated ions in comparison with recombi-nation rate coefficient of H3
+ could be the main reason for higher
charge particles densities. The error in rotational temperature
estimation could introduce a significant error to number density
too. An alternative explanation requires a significant overesti-
mation of the integral absorption coefficient of the D2H+ ortho
state transitions. We regard an error of this magnitude in the
theory as unlikely.
The measurements of D2H+ ion number densities were
repeated for different ratios of partial pressures of D2 and H2. In
Fig. 5 the D2H+(v = 0) ion number density in the plasma is plot-
tedas a function of relative numberdensity of D2 in respect to the
overall number density of D2 and H2, indicated as D2/(D2 + H2).
-
8/3/2019 P. Hlavenka et al- Near infrared second overtone cw-cavity ringdown spectroscopy of D2H^+ ions
6/7
P. Hlavenka et al. / International Journal of Mass Spectrometry 255256 (2006) 170176 175
Fig. 5. Average population of D2H+(v = 0) as a function of D2 to (D2 + H2) rel-
ative number densities in He-Ar-H2-D2 plasma at 7 mbar and 110W microwave
pulse. The measurement in pure D2 was not achievable because of an approxi-
mately 2% H2 content in the D2 gas bottle.
The relative population of D2H+ is in good agreement with the
model and the experimental data introduced by Farnik et al. [22].
4. Conclusions
The measurement of the transition frequencies wasguided by
ab initio theoretical predictions, which proved to be extremely
accurate. Interpretation of the results also relies on the accuracy
of the theoretical intensity calculations. Given that there is much
less intensity data to compare with, and a residual discrepancy
with the intensity of one measured D2H+ transition [22], it may
be necessary to seek further experimental confirmation of thecalculated absolute intensities before they can be completely
relied on for interpretation of the experiments.
From a plasma point of view this measurement presents a
simple but very powerful plasma diagnostics tool applicable in
hydrogen/deuterium containing plasmas, e.g., in ion sources.
The obtained data can be used to characterise the excitation and
kinetic temperature of ions in a RF ion trap, using laser induced
ion molecular reactions (LIR) with cheap and compact DFB
laser.
Acknowledgments
We thank Peter Macko for helpful discussions. This
work is a part of the research plan MSM 0021620834 that
are financed by the Ministry of Education of the Czech
Republic and partly was supported by Kontakt CZ-8/2004,
GACR (202/03/H162, 205/05/0390, 202/05/P095), GAUK-
278/2004/B-FYZ/MFF, GAUK-226/2005/B-FYZ/MFF.
References
[1] T.R. Geballe, T. Oka, Nature 384 (1996) 334.
[2] T. Oka, in: A.P. Roy (Ed.), Spectroscopy: Perspectives and Frontiers,
Narosa, New Delhi, 1997, pp. 116.
[3] T.R. Geballe, Phil. Trans. Roy. Soc. Lond. A 358 (2000) 2503.
[4] T.J. Millar, H. Roberts, A.J. Markwick, S.B. Charnley, Phil. Trans. Roy.
Soc. Lond. A 358 (2000) 2535.
[5] H. Roberts, E. Herbst, T.J. Millar, Astron. Astrophys. 424 (2004) 905.
[6] H. Roberts, E. Herbst, T.J. Millar, Astrophys. J. 591 (2003) L41.
[7] D. Gerlich, S. Schlemmer, Planet. Space Sci. 50 (2002) 1287.
[8] E. Roueff, J. Phys. Conf. Ser. 4 (2005) 1.
[9] E. Roueff, S. Tine, L. Coudert, G. Pineau des Forets, E. Falgarone, M.
Gerin, A&A 354 (2000) L63.
[10] C. Vastel, T.G. Phillips, H. Yoshida, Astrophys. J. 606 (2004) L127.[11] C. Vastel, T.G. Phillips, C. Ceccarelli, J. Pearson, Astrophys. J. 593
(2003) L97.
[12] T. Hirao, T. Amano, Astrophys. J. 597 (2003) L85.
[13] T. Amano, T. Hirao, J. Mol. Spectrosc. 233 (2005) 7.
[14] J. Ramanlal, O.L. Polyansky, J. Tennyson, Astron. Astrophys. 406 (2003)
383.
[15] J. Ramanlal, J. Tennyson, Mon. Not. Roy. Astron. Soc. 354 (2004) 161.
[16] N.G. Adams, D. Smith, Astrophys. J. 248 (1981) 373.
[17] J. Glosk, Int. J. Mass Spectrom. 139 (1994) 15.
[18] D. Gerlich, E. Herbst, E. Roueff, Planet. Space Sci. 50 (2002) 1275.
[19] M. Quack, Mol. Phys. 34 (1977) 477.
[20] M. Cordonnier, D. Uy, R.M. Dickson, K.E. Kerr, Y. Zhang, T. Oka, J.
Chem. Phys. 113 (2000) 3181.
[21] T. Oka, J. Mol. Spectrosc. 228 (2004) 635.
[22] M. Farnk, S. Davis, M.A. Kostin, O.L. Polyansky, J. Tennyson, D.J.Nesbit, J. Chem. Phys. 116 (2002) 6146.
[23] T. Oka, E. Epp, Astrophys. J. 613 (2004) 349.
[24] V. Kokoouline, C.H. Greene, Phys. Rev. A 68 (2003), 012703-1.
[25] F. Le Petit, E. Roueff, E. Herbst, Astron. Astrophys. 417 (2004) 993.
[26] R. Plasil, J. Glosk, V. Poterya, P. Kudrna, J. Rusz, M. Tichy, A. Pysa-
nenko, Int. J. Mass Spectrom. 218 (2002) 105.
[27] M. Larsson, Phil. Trans. Roy. Soc. Lond. A 358 (2000) 2433.
[28] M.J. Jensen, H.B. Pedersen, C.P. Safvan, K. Seiersen, X. Urbain, L.H.
Andersen, Phys. Rev. A 63 (2002).
[29] D. Smith, P. Spanel, Int. J. Mass Spectrom. 129 (1993) 163.
[30] A. Canosa, J.C. Gomet, B.R. Rowe, J.B.A. Mitchell, J.L. Queffelec, J.
Chem. Phys. 97 (1992) 1028.
[31] S. Laube, A. Le Padelleck, O. Sidko, C. Rebrion-Rowe, J.B.A. Mitchell,
B.R. Rowe, J. Phys.: At. Mol. Opt. Phys. 31 (1998) 2111.
[32] T. Gougousi, R. Johnsen, M.F. Golde, Int. J. Mass Spectrom. 149/150
(1995) 131.
[33] D. Smith, P. Spanel, Chem. Phys. Lett. 211 (1993) 454.
[34] M. Larsson, et al., Phys. Rev. Lett. 79 (1997) 395.
[35] V. Poterya, J. Glosk, R. Plasil, M. Tichy, P. Kudrna, A. Pysanenko,
Phys. Rev. Lett. 88 (2002) 044802.
[36] H. Kreckel, J. Mikosch, R. Wester, J. Glos k, R. Plasil, M. Motsch, D.
Gerlich, D. Schwalm, A. Wolf, J. Phys. Conf. Ser. 4 (2005) 126.
[37] B.J. McCall, A.J. Huneycutt, R.J. Saykally, T.R. Geballe, N. Djuric,
G.H. Dunn, J. Semaniak, O. Novotny, A. Al-Khalili, A. Ehlerding, F.
Hellberg, S. Kalhori, A. Neau, R. Thomas, F. Osterdahl, M. Larsson,
Nature 422 (6931) (2003) 500.
[38] S. Kalhori, A. Al-Khalili, A. Neau, R. Thomas, A. Ehlerding, F. Hell-
berg, M. Larsson, A. Larson, A.J. Honeycutt, N. Djuric, G.H. Dunn, J.
Semaniak, O. Novotny, A. Paal, F. Osterdahl, A.E. Orel, Phys. Rev. A
69 (2004) 022713.
[39] B.J. McCall, A.J. Huneycutt, R.J. Saykally, N. Djuric, G.H. Dunn, J.
Semaniak, O. Novotny, A. Al-Khalili, A. Ehlerding, F. Hellberg, S.
Kalhori, A. Neau, R. Thomas, A. Paal, F. Osterdahl, M. Larsson, J.
Phys. Conf. Ser. 4 (2005) 92.
[40] H. Kreckel, M. Motsch, J. Mikosch, J. Glosik, R. Plasil, S. Altevogt, V.
Andrianarijaona, H. Buhr, J. Hoffmann, L. Lammich, M. Lestinsky, Y.
Nevo, S. Novotny, D.A. Orlov, H.B. Pedersen, F. Sprenger, J. Toker, R.
Wester, D. Gerlich, D. Schwalm, A. Wolf, D. Zajfman, Phys. Rev. Lett.
(2005), submitted for publication.
[41] B.J. McCall, A.J. Huneycutt, R.J. Saykally, N. Djuric, G.H. Dunn, J.
Semaniak, O. Novotny, A. Al-Khalili, A. Ehlerding, F. Hellberg, S.
Kalhori, A. Neau, R.D. Thomas, A. Paal, F. Osterdahl, M. Larsson,
Phys. Rev. A 70 (2004) 052716.
[42] V. Kokoouline, C.H. Greene, Phys. Rev. Lett. 90 (13) (2003) 133201.
-
8/3/2019 P. Hlavenka et al- Near infrared second overtone cw-cavity ringdown spectroscopy of D2H^+ ions
7/7
176 P. Hlavenka et al. / International Journal of Mass Spectrometry 255256 (2006) 170176
[43] V. Kokoouline, C.H. Greene, J. Phys. Conf. Ser. 4 (2005) 74.
[44] R. Plasil, P. Hlavenka, P. Macko, G. Bano, A. Pysanenko, J. Glosk, J.
Phys. Conf. Ser. 4 (2005) 118.
[45] J. Mikosch, H. Kreckel, R. Wester, J. Glosk, R. Plasil, D. Gerlich, D.
Schwalm, A. Wolf, J. Chem. Phys. 121 (22) (2004) 11030.
[46] J. Glosk, P. Hlavenka, R. Plasil, F. Windisch, D. Gerlich, A. Wolf, H.
Kreckel, Phil. Trans. Roy. Soc. Lond. A (2006), submitted for publica-
tion.
[47] D. Gerlich, F. Windisch, J. Glosk, P. Hlavenka, R. Plasil, Phil. Trans.R. Soc. Lond. A (2006), submitted for publication.
[48] S. Schlemmer, O. Asvany, E. Hugo, Phil. Trans. Roy. Soc. Lond. A
(2006), submitted for publication.
[49] O.L. Polyansky, J. Tennyson, J. Chem. Phys. 110 (1999) 5056.
[50] T. Amano, T. Hirao, J. Mol. Spectrosc. 233 (2005) 7.
[51] H. Linnartz, D. Pfluger, O. Vaizert, P. Cias, P. Birza, D. Khoroshev, J.P.
Maier, J. Chem. Phys. 116 (2002) 924.
[52] D. Romanini, A.A. Kachanov, F. Stoeckel, Chem. Phys. Lett. 270 (1997)
538.
[53] J. Morville, D. Romanini, A.A. Kachanov, M. Chenevier, Appl. Phys B
78 (2004) 465.
[54] P. Macko, G. Bano, P. Hlavenka, R. Plasil, V. Poterya, A. Pysanenko,
O. Votava, R. Johnsen, J. Glosk, Int. J. Mass Spectrosc. 233 (2004)
299.
[55] P. Macko, R. Plasil, P. Kudrna, P. Hlavenka, V. Poterya, A. Pysanenko,G. Bano, J. Glosk, Czechoslovak J. Phys. 52 (2002) D695.
[56] P. Macko, G. Bano, P. Hlavenka, R. Plasil, V. Poterya, A. Pysanenko,
K. Dryahina, O. Votava, J. Glosk, Acta Phys. Slovaca 54 (3) (2004)
263.
[57] B.F. Ventrudo, D.T. Cassidy, Z.Y. Guo, S. Joo, S.S. Lee, T. Oka, J.
Chem. Phys 100 (1994) 6263.
[58] L. Neale, S. Miller, J. Tennyson, Astrophys. J. 464 (1996) 516.
[59] P.J. Fox, R.E. Scholten, M.R. Walkiewicz, R.E. Drullinger, Am. J. Phys.
67 (1999) 624.
[60] P. Macko, D. Romanini, S.N. Mikhailenko, O.V. Naumenko, S. Kassi,A. Jenouvrier, V.G. Tyuterev, A. Campargue, J. Mol. Spectrosc. 227
(2004) 90.
[61] J. Tennyson, P. Barletta, M.A. Kostin, O.L. Polyansky, N.F. Zobov, Spec-
trochim. Acta A 58 (2002) 663.
[62] J. Ramanlal, PhD Thesis, University of London (2005).
[63] A. Faure, J. Tennyson, Mon. Not. Roy. Astron. Soc. 340 (2003)
468.
[64] A. Faure, J. Tennyson, J. Phys. B: At. Mol. Opt. Phys. 35 (2002)
3945.
[65] M. McFarland, D.L. Albritton, F.C. Fehsenfeld, E.E. Ferguson, A.L.
Schmeltekopf, J. Chem. Phys. 59 (1973) 6610.
[66] G.H. Wannier, Bell Syst. Tech. J. 32 (1953) 170.
[67] L.A. Viehland, A.A. Viggiano, E.A. Mason, J. Chem. Phys. 95 (1991)
7286.
[68] J. Glosk, V. Skalsky, C. Praxmarer, D. Smith, W. Freysinger, W.Lindinger, J. Chem. Phys. 101 (1994) 3792.
top related